1. Field of the Invention
The present invention relates to stage systems, exposure apparatus, and device manufacturing methods, and more particularly to a stage system comprising a stage main body that moves along a movement plane of a supporting member, a mover that is connected to the stage main body, and a stator that is provided independent of the supporting member of vibration, an exposure apparatus that comprises the stage system as a drive system for at least one of a mask and a substrate, and a device manufacturing method that uses the exposure apparatus when exposure is performed.
2. Description of the Related Art
In a conventional photolithographic process for manufacturing devices such as semiconductors and liquid crystal display devices, projection exposure apparatus of a sequential moving type such as a reduction projection exposure apparatus based on a step-and-repeat method (a so-called stepper) that reduces and transfers a pattern formed on a mask or a reticle (hereinafter generally referred to as a xe2x80x9creticlexe2x80x9d) onto a substrate such as a wafer or a glass plate (hereinafter generally referred to as a xe2x80x9cwaferxe2x80x9d) coated with a resist or the like via a projection optical system, and a scanning projection exposure apparatus based on a step-and-scan method (a so-called scanning stepper), which is an improvement of the stepper, are being widely used.
For example, in a scanning stepper, a reticle stage supporting member is a movement reference of a reticle stage on which a reticle is held. And, since it plays an important part when setting an imaging plane on which an image of a pattern formed on the reticle is formed by a projection optical system, vibration of the reticle supporting member is preferably suppressed as much as possible, even when the reticle stage is being driven.
In addition, with a wafer stage of a projection exposure apparatus, in most cases a wafer table that can be driven at least in a Z tilt is arranged on an XY stage that can be driven in an XY plane in order to make the wafer surface coincide with the image plane on which the image of the pattern on the reticle is formed, and the wafer is held on the wafer table. In such cases, when vibration occurs in a wafer stage supporting member that exceeds a predetermined amount, the vibration cannot be attenuated sufficiently, which causes the control accuracy of the position of the wafer table in the Z-axis direction to decrease.
Therefore, when the reticle stage or the wafer stage is driven, such as by a linear motor, in order to keep a reaction force that occurs when the stage is driven by the linear motor from traveling to the stage supporting member, the stator of the linear motor on which the reaction force due to the drive of the stage acts is to be separated from the stage supporting member, or a so-called counter mass mechanism where the stator moves for conservation of momentum by the action of the reaction force is to be employed. With the above arrangement, the stage supporting member is isolated from vibration caused by the reaction force that occurs when the stage is driven.
In addition, in order to prevent the stage supporting member from vibrating due to vibration from the floor, dampers are preferably arranged in between the stage supporting member and the floor so as to isolate vibration with respect to the stage supporting member.
In both the reticle stage and the wafer stage, a linear motor is used in many cases as a means for driving in at least a long stroke direction (normally a direction along one axis within a horizontal plane). With such a linear motor, permissible relative displacement in between the mover and the stator in a direction perpendicular to the horizontal surface (a height direction) is small, such as around the range of xc2x10.5 mm, which is the limit for obtaining effective thrust.
Meanwhile, as the damper referred to above, in order to obtain a sufficient vibration attenuation effect, an AVIS (a vibration isolator the performs vibration attenuation by a combination of a mechanical damper that can bear heavy weight such as an air damper and an electromagnetic actuator such as a voice coil motor) is frequently employed. That is, the AVIS proactively drives the stage supporting member, so as to prevent the vibration in the stage bed caused by the vibration from the floor. With the AVIS, however, the permissible movable stroke from a neutral position to a position where a stopper (mechanical stopper) that mechanically limits its drive is arranged is around xc2x13 mm. Therefore, when the AVIS goes out of control, since the drive strokes of the stage supporting member by the AVIS exceeds the above permissible range of the linear motor the linear motor may consequently be damaged due to the stator and the mover of the linear motor coming into contact with each other.
As a method of preventing such a situation, for example, guide portions of the stator and the mover of the linear motor may each be arranged separately from a guide surface on the stage supporting member. With such an arrangement, however, since the guide surface of each of the stages is originally arranged on the stage supporting member, it becomes difficult to maintain a suitable positional relationship between the guide surfaces of the stages and the guide portions of the stator and mover of the linear motor. And, as a consequence, the guide portions of the stator and the mover of the linear motor could be damaged.
Therefore, in the conventional art, maintenance had to be frequently preformed on the linear motor or on its guide portion. This, however, leads to an increase in the downtime of the exposure apparatus, which in turn, becomes a cause of decreasing the productivity of a device as an end product.
The present invention was made under such circumstances, and has as its first object to provide a stage system that can stably drive a stage main body for a long period of time.
In addition, the second object of the present invention is to provide an exposure apparatus that can improve operation efficiency.
Moreover, the third object of the present invention is to provide a device manufacturing method that can improve productivity of a device.
According to the first aspect of the present invention, there is provided a stage system comprising: a stage main body that is movable along a movement plane of a supporting member; a mover that is coupled with the stage main body; a stator that cooperates with the mover to move the stage main body, the stator being provided independent of the supporting member regarding vibration; a driver that drives the supporting member; and a releaser that releases a coupling between the stage main body and the mover when a drive amount of the supporting member by the driver exceeds a predetermined amount.
With the stage system, the stage main body is driven along the movement plane of the supporting member, with the stator provided independent of the supporting member regarding vibration cooperating with the mover coupled with the stage main body. The driver drives the supporting member, however, when the drive amount of the driver exceeds a predetermined value, the coupling between the stage main body and the mover is released. That is, when the drive amount of the supporting member exceeds a predetermined value, the releaser releases the coupling between the stage main body and the mover before the mover coupled with the stage main body comes into contact with the stator and both parts are put under a large stress. As a consequence, the mover and stator can be kept from being damaged from the contact. In addition, since the stator is provided independent of the supporting member regarding vibration, the reaction force generated in the stator when the stage main body is driven does not make the supporting member vibrate, therefore, position control of the stage main body moving along the movement plane of the supporting member can be performed with high precision. Accordingly, with the stage system, the stage main body can be driven stably, for over a long period of time.
In this case, the direction in which the driver drives the supporting member is not limited in particular. For example, the driver can drive the supporting member in a direction substantially perpendicular to the movement plane.
With the stage system in the present invention, various methods of coupling the stage main body and the mover and configurations of a releaser can be considered. For example, the stage main body and the mover may have a magnetic coupling, and the releaser may release the magnetic coupling, or the stage main body and the mover may have a coupling by vacuum chucking force, and the releaser may release the coupling by vacuum chucking force.
With the stage system in the present invention, it can comprise a support mount that is provided independent of the supporting member regarding vibration, and the stator can be coupled with the support mount.
With the stage system in the present invention, it can comprise a support mount that is provided independent of the supporting member regarding vibration, and the stator can be movably supported by the support mount.
In this case, the stator that is supported movably by the support mount can move in a direction opposite to a drive direction of the stage main body due to a reaction force generated when the stage main body is driven.
With the stage system in the present invention, when the stator is movably supported by the support mount, the stage system can further comprise a position correction mechanism that corrects a positional change of the stator occurring when the stage main body moves.
With the stage system in the present invention, when the stator is movably supported by the support mount, an acting point of a cooperative drive force of the stator and the mover can coincide with a center of gravity of the stage main body and a center of gravity of the stator, and the releaser can release the coupling between the stage main body and the mover when a positional displacement between the movement plane of the supporting member and a movement plane of the stator on the support mount exceeds a predetermined value due to the driver driving the supporting member.
With the stage system in the present invention, the stage main body and the mover can have a coupling by suction force, and the releaser can include an on/off mechanism that stops generating the suction force when it detects the mover coming into contact with the stator due to the driver driving the supporting member.
With the stage system in the present invention, it can further comprise an elastic member that has a degree of rigidity that avoids mechanical damage in the stage system when the releaser releases the coupling, and couples the stage main body and the mover.
According to the second aspect of the present invention, there is provided a first exposure apparatus that transfers a pattern formed on a mask onto a substrate, the exposure apparatus comprising: a first drive system that drives the mask; and a second drive system that drives the substrate, whereby the stage system in the present invention is used as at least one of the first drive system and the second drive system in the exposure apparatus.
In the exposure apparatus, the stage system in the present invention that stably drives the stage main body for over a long period of time is used in at least one of the first drive system, which drives the mask, and the second drive system, which drives the substrate. Therefore, at least one of the mask and the substrate can be stably driven for over a long period of time, and the overlay accuracy of the mask and the substrate can be favorably maintained. In addition, in the stage system, since the stator and the mover of the driver that drives the stage main body are not likely to be damaged by coming into contact, maintenance is not required. Accordingly, the downtime of the exposure apparatus can be reduced, and as a result the operation rate can be improved.
According to the third aspect of the present invention, there is provided a second exposure apparatus that exposes a photosensitive object with an energy beam and forms a predetermined pattern on the photosensitive object, the exposure apparatus comprising: at least one object stage movable along a first movement plane holding the photosensitive object; a first stage driver that has a first mover coupled with the object stage and a first stator driving the object stage by a driving force generated by physical interaction with the first mover; and a first releaser that releases a coupling between the object stage and the first mover when the first mover and the first stator come into contact due to relative displacement of the first movement plane with respect to the first stator.
In the exposure apparatus, the first stage driver drives the object stage coupled with the first mover by a suction force along the first movement plane, by a drive force generated by physical interaction between the first mover and the first stator (such as an electromagnetic interaction). And, when the first mover and the first stator come into contact due to relative displacement of the first movement plane with respect to the first stator for some reason, the releaser releases the coupling between the first mover and the object stage. Therefore, in the second exposure apparatus, damage in the first stator and the first mover of the first driver caused by coming into contact can be almost prevented, which reduces the maintenance frequency of the first stage driver since maintenance on the first stage driver due to the first stator coming into contact with the first mover will not be required. Accordingly, the downtime of the exposure apparatus can be reduced, and as a result the operation rate can be improved.
In this case, the object stage and the first mover can have a coupling by suction force, and the first releaser can release the coupling between the object stage and the first mover by releasing the suction force.
With the second exposure apparatus in the present invention, the first movement plane can be formed on a supporting member that is isolated from the first stator regarding vibration.
With the second exposure apparatus in the present invention, a plurality of object stages can be provided, and the first stage driver can have a plurality of first movers individually coupled by suction force with each of the object stages, and at least one of the first stator that can generate the driving force driving each of the object stages by physical interaction with each of the first movers, and the first releaser can release the suction force between at least a specific first mover and its corresponding object stage when the specific first mover comes into contact with its corresponding first stator.
In this case, the exposure apparatus can further comprise: a projection optical system that projects the energy beam emitted from a mask, which is an original plate of the pattern, on the photosensitive object; a focus detection system that detects a position of the photosensitive object held on each of the object stages in a direction of an optical axis of the projection optical system; a position measurer that measures a position of each of the object stages within a plane perpendicular to the optical axis; and an adjuster that adjusts a positional relationship between the movement plane and each of the object stages in the direction of the optical axis, based on a map regarding a position of each of the stages and a positional relationship between at least two of the object stages, measurement results of the position measurer, and detection results of the focus detection system.
With the second exposure apparatus in the present invention, it can further comprise: a mask stage that is movable along a second movement plane holding a mask, which is an original plate of the pattern; a second stage driver that has a second mover coupled with the mask stage and a second stator driving the mask stage by a driving force generated by physical interaction with the second mover; and a second releaser that releases a coupling between the mask stage and the second mover when the second mover and the second stator come into contact due to relative displacement of the second movement plane with respect to the second stator.
In this case, the mask stage and the second mover can have a coupling by suction force, and the second releaser can release the coupling between the mask stage and the second mover by releasing the suction force.
With the second exposure apparatus in the present invention, the second movement plane can be formed on a supporting member that is isolated from the second stator regarding vibration.
With the second exposure apparatus in the present invention, the suction force of the exposure apparatus can be one of a vacuum chucking force and a magnetic suction force.
In addition, in a lithographic process, by performing exposure using one of the first and second exposure apparatus in the present invention, the downtime of the exposure apparatus can be reduced, which can improve the productivity of the devices. Accordingly, in the present invention, furthermore from another aspect, there is provided a device manufacturing method using one of the first and second exposure apparatus in the present invention.